NSW Dog Bite - Who Pays Vet Bill?

My generous friend looked after my dog while I was on holiday last week. Her dog and my dog (pets) have always got on well with no problems and she has looked after him numerous times before.

The night before we came home, the 2 dogs were sleeping in their bedroom and for an unknown reason my dog bit her dog. Her dog was old and had no teeth so no protection in her mouth. Sadly, this meant that the laceration was deep and after surgery the decision was made to end her suffering and put her to sleep.

I offered to help cover the vet bill but as it turns out it is $1226. I really can't afford that much but don't mind paying half. If I offer her half, how do I stand legally? Is she within her rights to ask me to pay the whole bill as it was my dog or is it her responsibility as it was in her house under her care?

 

Thankyou, that is very useful.